Air assisted fast return stroke for rivet setting tool

ABSTRACT

A rivet setting tool is provided including a pulling head and a jaw case connected to the pulling head such that the jaw case is driven by the pulling head to engage a rivet mandrel. Air is supplied to the pulling head to return the pulling head to its original position after a rivet has been set. A remote intensifier is provided including an air piston disposed in a piston chamber and a rod connected to the air piston and extending into a ram housing which is connected to a hydraulic passage which is connected to the pulling head. A first supply of pressurized gas communicates with a first end of the piston chamber and a second supply of pressurized gas communicates with a second end of the piston chamber for rapidly returning the air piston to the retracted position in combination with the air pressure applied to the pulling head. The second end of the piston chamber is vented to prevent to much pressure build up pushing the piston to the retracted position.

This application claims benefit of Provisional application 60/105,074,filed Oct. 21, 1998.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to riveting machines, and moreparticularly to a portable riveting system with an autofeed mechanismfor automatically supplying rivets to an application tool and methodsfor operating the riveting system.

2. Background and Summary of the Invention

A blind rivet comprises a tubular rivet body in which is mounted amandrel having a head portion at the narrow end of the stem so that whenthe mandrel is pulled back in the rivet, it upsets the rivet. Whenpulling-back of the mandrel is resisted with a predetermined force, themandrel breaks off. A riveter that operates with such rivets typicallyhas a housing formed at its front end with an aperture through which therivet mandrel is engaged. Within the housing is a chuck that engagestightly around the mandrel and an actuating mechanism or pulling headwhich pulls the chuck backwardly, thereby upsetting the rivet andbreaking off the mandrel.

In rivet setting machines, the operator sets a rivet held in the nose ofthe rivet tool by pulling a trigger. The remaining spent mandrel isdrawn through the tool and through a collection tube into a collectionbox. A proximity switch senses the spent mandrel just before it entersthe collection box.

There are a variety of different types of tools, both manual andpowered, that are used to set pull-type blind fasteners. For industrialproduction, it is desirable to use a power tool that may have anair/hydraulic or electrical power assist to pull the mandrel stem. Thisfacilitates the rivet setting operation.

It is known to automate the process of feeding rivets to the rivetertool, as for example shown in U.S. Pat. Nos. 4,754,643 and 4,747,294,commonly assigned. It is also known to automate the mandrel collectionprocess as taught, for example, in U.S. Pat. No. 4,972,985, alsocommonly assigned. The most common approach to automatic rivet feed anddisposal uses hydraulically or pneumatically powered mechanisms forguiding blind rivets to the riveting tool and extracting broken offmandrels therefrom.

Common shortcomings of prior art apparatus for autofeeding of rivets tothe riveting tool is the failure of such systems to take into accountthe need for rapid adjustment, improved maintenance, serviceability andrapid change-over capability. In addition, ways are constantly beingsought which speed up the reload capabilities as well as speeding up therivet setting process.

In furthering the above and additional objects, the present inventionprovides a rivet setting tool including an automatic rivet deliverydevice for transferring a rivet from a rivet passage to a nose piece ofthe rivet setting tool. The rivet delivery device is air driven toextend forwardly of the nose of the setting jaws, and rotates to presenta rivet in front of the jaws and then transfers the rivet into the jawsin known manner. The rivet delivery device extends through the rear of ahand tool so that its angular rotation can be adjusted withoutdisassembling the tool. The stroke length of the rivet delivery devicecan also be easily adjusted.

A further feature of the rivet delivery device is the provision of adouble-acting piston driven in both directions by positive air pressureto extend and rotate the delivery device in front of the nose piece andreturning the rivet delivery device after rivet transfer. The use of adouble-acting piston greatly enhances the speed at which the rivetdelivery device can operate. Furthermore, the ability to adjust thestroke length or angular rotation of the rivet delivery device withoutdisassembling the entire tool, greatly increases the ability to rapidlyadjust the rivet delivery device in order to change over to differentsized rivets or to simply make minor adjustments.

The system of the present invention also includes a portable housing anda hand tool connected to the portable housing. The portable housingincludes electronic and pneumatic modules for controlling the supply ofelectric and pneumatic power to a rivet feeding device and to the handtool. In response to the activation and release of a trigger switch onthe hand tool, blind rivets are supplied from a feeder bowl via a trackto a reciprocating escapement mechanism which transfers successiverivets from the track to a tube through which they are moved bycompressed air to a rivet delivery device located on the hand tool. Thedifferent components of the portable autofeed riveting system aredesigned to be separately detachable from the housing as a modular unitso that the independent modular units can be easily disassembled fromthe housing and can be replaced by replacement modules so that the rivetsetting tool experiences as little down time as necessary.

The portable rivet setting system of the present invention is alsoprovided with an escapement mechanism which includes a nesting blockslidably received by a housing and including a recessed portion forreceiving and supporting a fastener therein. The nesting block can beeasily changed in just a few seconds in order to accommodate a differentsized rivet. The ability to rapidly change the nesting block reduces theamount of time required for change over, and thereby increases theefficiency of the overall riveting system.

The rivet setting tool of the present invention is provided with apulling head which employs air pressure to return the piston to its fullforward position and is connected to a remote intensifier via ahydraulic hose. The remote intensifier includes an air piston disposedin a piston chamber and a hydraulic ram connected to the air piston andextending into a hydraulic passage connected to the hydraulic hose. Theair piston has a larger cross-sectional area than the hydraulic ramwhich allows the intensifier to generate a large hydraulic pressure froma relatively small air pressure. A first supply of pressurized gascommunicates with a first end of the piston chamber and a second supplyof pressurized gas communicates with a second end of the piston chamber.The second end of the piston chamber is vented to atmosphere around apiston chamber sleeve. The second supply of pressurized gas is utilizedto provide a low pressure bubble of air on top of the air piston inorder to assist the return of the piston of the pulling head to aretracted position while increasing the speed of the piston's return.The speed at which the air piston returns to its retracted position isdirectly related to the speed at which the rivet setting tool is resetin order to receive and set another rivet.

The rivet setting tool of the present invention is also provided with acontrol strategy whereby when a trigger is depressed, a controllerinstructs the remote pulling head back in order to set a rivet. The jawsengage the rivet mandrel and start the setting process. As hydraulicpressure builds, a high and a low pressure switch witness the increasein pressure as setting occurs, and set a latch. When the high pressureswitch drops low again, the controller deduces that the rivet has set.Activation pressure to the remote intensifier is then stopped and returnair is started causing the tools pulling head to return concurrently.The controller starts a mandrel collection window to monitor thecollection of the mandrel. As the tool jaws open, the mandrel isreleased and a vacuum draws the mandrel past a mandrel sensor and intothe collection bin. As the mandrel passes the mandrel sensor, themandrel collection window is reset. The rivet delivery device loads anew rivet into the nose piece of a tool as the tool returns fullforward. Since the high setting/loading speed makes it possible to haveas many as two mandrels in the collection path at once, two separatemandrel collection windows are required, with the first becomingavailable for the third rivet as soon as the first mandrel passes themandrel sensor. These two timers (windows) are continuously reused againand again throughout the process. If a jam were to inhibit collection ofthe mandrels as witnessed by the window timing out before the mandrelsensor detects a mandrel's passage, the system will shut down.

The pressure switches allow the system of the present invention todetermine if there is a rivet loaded in the nose of the tool since nosensor is provided in the nose of the tool. During the setting process,the system confirms that a rivet has been loaded by monitoring thepressure switches. If the switches detect pressure within a short periodof time, i.e., within an amount of time for the pulling head to travelalmost fully back, it knows a rivet was presented and proceeds as above.If there were no rivet in the nose of the rivet setting tool, when thetrigger is activated, the switches would see no build-up of pressurewithin the setting window and would not start a mandrel collectionwindow, but would rather initiate the rivet delivery device reloadingsequence.

Further areas of applicability of the present invention will becomeapparent from the detailed description provided hereinafter. It shouldbe understood however that the detailed description and specificexamples, while indicating preferred embodiments of the invention, areintended for purposes of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is perspective view of an operator using the portable autofeedriveting system of the present invention;

FIG. 2 is a perspective view of the portable autofeed riveting system ofthe present invention, illustrating the different modular components ofthe system according to the principles of the present invention;

FIG. 3 is a schematic view of each of the modules of autofeed rivetingsystem of the present invention and showing the connectionstherebetween;

FIG. 4 is a perspective view from the right side of the rivet settingtool according to the principles of the present invention;

FIG. 5 is a perspective view from the left side of the rivet settingtool according to the principles of the present invention;

FIGS. 6-8 each provide a right side perspective view of a rivet settingtool according to the principles of the present invention with the rivetdelivery device in three different operating positions, respectively;

FIGS. 9-11 are left side perspective views illustrating the rivetdelivery device in three different operating positions, respectively;

FIG. 12 is a cross-sectional view of the rivet delivery device accordingto the principles of the present invention;

FIG. 13 is a partial sectional view of the cam sleeve of the rivetdelivery device according to the principles of the present invention;

FIG. 14 is a cross-sectional view taken along line 14—14 of FIG. 12;

FIG. 15 is an end view of the piston of the rivet delivery deviceaccording to the principles of the present invention;

FIG. 16 is a side view of a rivet delivery device adjustment toolaccording to the principles of the present invention;

FIG. 17 is a perspective view of a feeder bowl and escapement mechanismaccording to the principles of the present invention;

FIG. 18 is a perspective view from a different angle of the feeder bowland escapement mechanism shown in FIG. 17;

FIG. 19 is a perspective view of the escapement mechanism of the presentinvention with the top plate removed;

FIG. 20 is a perspective view of the escapement mechanism shown in FIG.19 with the top plate disposed in its assembled position;

FIG. 21 is a top view of the rivet guide track and escapement mechanismaccording to the principles of the present invention;

FIG. 22 is a side view of the escapement mechanism according to theprinciples of the present invention illustrating the thumb screw forsecuring the top plate in its assembled position;

FIG. 23 is a perspective view of the nesting block of the escapementmechanism according to the principles of the present invention;

FIG. 24 is a side view of the nesting block shown in FIG. 23,illustrating the slot which receives the head of the driver rodaccording to the principles of the present invention;

FIG. 25 is a cross-sectional view of the remote intensifier according tothe principles of the present invention;

FIG. 26 is a perspective view of the portable autofeed riveting systemaccording to the principles of the present invention, illustrating theconnections of the umbilical assembly of the present invention;

FIG. 27 is an illustration of a typical rivet set signature with thehydraulic pressure plotted over time and illustrating the window duringwhich the detection of a mandrel is sensed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIGS. 1-27, a detailed description of the portableautofeed riveting system 10 of the present invention will be described.The portable autofeed riveting system 10 includes a rivet setting tool12 connected via an umbilical 14 to a portable housing 16 which houses arivet feeder bowl 18 preferably of the vibratory type. The rivet feederbowl 18, best shown in FIGS. 17 and 18, is automatically fed rivets inbulk by a rivet hopper 20 which is disposed in a top portion of thehousing 16 and is covered by a pivotally mounted cover 22. Rivetsdelivered from the bulk supply in the vibratory bowl are stacked in aninclined feed track 24, which accumulates a supply of rivets forescapement mechanism 26. The rivet escapement mechanism 26, which willbe described in greater detail herein, includes a reciprocating nestingblock 28 (see FIGS. 17-24) which periodically advances a rivet to arivet delivery tube 30. The rivet delivery tube 30 extends throughumbilical 14 and delivers rivets, via pneumatic pressure, to the rivetsetting tool 12 which will be described in greater detail herein.

The portable autofeed riveting system 10 also includes an electricalpanel/module 34 to which are mounted key electrical components of theriveting system. Electrical control module 34 is connected to anexternal power source 35. A pneumatic panel/module 36 is provided whichsupports key pneumatic components of the riveting system. The pneumaticcontrol module 36 is connected to a main source of pressurized air 37such as a compressor. The electrical panel 34 and pneumatic panel 36 areboth supported by slots disposed in the bottom and top of the housing16. Electrical panel 34 includes a plurality of terminals which areengaged by electrical connectors which connect to the remainingcomponents and modules of the riveting system 10. A remote intensifiermodule 40 is provided in the housing 16 and provides hydraulic pressurethrough a hydraulic hose 42 which is disposed in the umbilical 14 and isconnected to an installation tool including a pulling head 43 whichengages a jaw case 44 for setting a rivet.

A barrier 46 is provided in the housing 16 for partitioning the housing16 into two separate enclosed portions. The first enclosed portionhouses the electrical and pneumatic panels 34, 36, while the secondportion houses the rivet feeder bowl 18 escapement mechanism 26, rivethopper 20, remote intensifier 40, and mandrel collection system 47. Themandrel collection system 47 includes a collection bin 48 and a mandrelreturn tube 49 which is connected to the rivet setting tool 12 andreceives a mandrel which is released by the jaw case of the rivetsetting tool 12. A mandrel sensor 50 is provided adjacent to the mandrelreturn line 49 for sensing the return of a mandrel into the mandrelcollection system 47.

An operator interface 56 is optionally mounted to the housing 16, or ifused in special applications such as with a workbench, can be pulledaway from the housing 16 with a tether-like electrical cord 58, as bestshown in phantom in FIG. 2. The operator interface 56 can be providedwith a magnetized backing, a hook and loop-type fastener, or other knownfastening systems, for supporting the operator interface to the housing16 or to other surfaces such as a workbench or a cabinet.

The rivet setting tool 12 includes a rivet delivery device 60 as shownin FIGS. 3-12. The rivet delivery device 60 is mounted within a handheldhousing 62 which includes a handle portion 64 with a trigger switch 66.A grip strap 68 is mounted to the handle portion 64 and is adjustable inorder to assist an operator in holding onto the rivet setting tool 12.The grip strap 68 can be mounted on either side of the housing 62 asillustrated in FIGS. 4 and 5.

As best shown in FIG. 12, the rivet delivery device 60 includes a bodytube 70 which receives a rod 72 which supports a delivery arm 74. Therod 72 of rivet delivery device 60 is connected to a piston 76 whichreciprocates within body tube 70. The rod 72 has a threaded end portion78 which is threadedly attached to an internally threaded portion 80 ofthe piston 76. A piston stop member (cam actuator) 82 is provided withinternal threads which engage threaded portion 78 of rod 72. The rod 72has a main body portion provided with a generally round cross-sectionwith dual opposing flats (best shown in the cross-section view of FIG.14) and is slidably received within a corresponding opening 86 which hasa generally round cross section with dual opposing flats in a camfollower 88. Cam follower 88 supports a pair of dowel pins 90 onopposite sides thereof which engage a cam slot 92 disposed in a radiallyoutwardly disposed concentric cam sleeve 94. Cam sleeve 94 includes aninternal shoulder portion 96 which provides a seat portion for a coilspring 98 which is disposed between cam follower 88 and shoulder portion96. Spring 98 biases the cam follower 88 in the direction of arrow A asshown in FIG. 12 so that dowel pins 90 each engage an end of cam slots92.

The rivet delivery device 60 includes a rear cylinder cap 100 which isprovided with a first fitting 102 which communicates with a pistonchamber 104 through passage 106 for providing pressurized gas to thechamber 104 and thereby driving piston 76 in the direction of arrow B. Asecond fitting 108 is provided in the cylinder cap 100 whichcommunicates via a passage 109 with a tube 110 which extends into acentral passage 112 in rod 72. An O-ring 113 is provided between thetube 110 and central passage 112. A pair of pneumatic tubes 115 a, 115 b(shown in FIG. 3) are connected to first and second fittings 102, 108,respectively, for controllably operating the rivet delivery device 60.As pressurized air is delivered through pneumatic tube 115 a and firstfitting 102, the piston 76 is driven in the direction of arrow B wherebyrod 72 extends out of the body tube 70. As the piston stop 82 engagescam follower 88, cam follower 88 presses against the bias of the spring98. As the dowel pins 90 follow the generally helical profile of the camslots 92, the cam follower 88, and thus the rod 72 are caused to rotate.

With reference to FIGS. 6 and 9, the rod 72 and delivery arm 74 of rivetdelivery device 60 are in the retracted position such as shown in thecross-sectional view of FIG. 12. In the retracted position, a transferbushing 114 which is provided in the end of delivery arm 74 is disposedopposite the receiver bushing 116 of the rivet delivery tube 30. Asuction pressure is applied through pneumatic tube 115 b and secondfitting 108 which provides a suction through central passage 112 in rod72 which communicates with a passage 118 in delivery arm 74 which inturn communicates with a central passage 120 in transfer bushing 114.The suction force retains the rivet R after the rivet is transportedfrom the escapement mechanism 26 by the rivet delivery tube 30. At thistime, the suction force through second fitting 108 is maintained whilepressurized gas is provided through first fitting 102 to cause piston 76to slide along body tube 70 until piston stop 82 engages cam follower88. FIGS. 7 and 10 illustrate the orientation of the rod 72 and deliveryarm 74 just as the piston stop 82 engages the cam follower 88. At thistime, piston stop 82 causes cam follower 88 to move relative to camsleeve 94 against the biasing force of spring 98 so that the dowel pins90 travel along generally helical cam slots 92 causing cam follower 88and rod 72 to rotate relative to cam sleeve 94, so that rod 72 anddelivery arm 74 are oriented as illustrated in FIGS. 8 and 11. As thepiston 76 reaches its fullest extended position, the rod 72 is fullyextended and delivery arm 74 is rotated to be aligned with the nosepiece 124 of the pulling adapter and jaw case mechanism 43/44. Apositive pressure is then induced through second fitting 108 to blow therivet R across the gap into the nose piece 124 of the installation tool43/44 where it is held in place by vacuum.

A third fitting 128 is provided in the rivet delivery device 60 and isconnected to a pneumatic tube 130 (see FIG. 3). Third fitting 128communicates with a second end of piston chamber 104 for providingpressurized gas to the second side of the piston 76 to force the piston76 to its retracted position whereby the delivery arm 74 is againaligned with the receiver bushing 116 of rivet delivery tube 30 forbeginning a reload cycle.

The rear cylinder cap 100 is provided with an O-ring 132 for sealing afirst end of piston chamber 104. The cam sleeve 94 is provided with apair of O-rings 134 which sealingly close off the second end of pistonchamber 104. A front end cap 136 is provided in an open end of camsleeve 94. A TEFLON washer 138 and seal/seal sleeve assembly 140 areprovided around the rod 72 within the open end of cam sleeve 94. Piston76 is provided with a magnetic ring 142 which works in combination withan external sensor (not shown) which senses the position of piston 76.As the piston 76 returns to the retracted position, the external sensorsends a signal to the controller which then activates the escapementmechanism 26 to send another rivet to the tool.

The piston 76 is provided with a pair of bores 146, as shown in FIG. 15.The bores 146 are adapted to be engaged by a rivet delivery deviceadjustment tool 150 as shown in FIG. 16. Adjustment tool 150 includes acylindrical main body 152 and a handle 154 mounted to the main body 152by a cap screw 156. A pair of dowel pins 158 are inset in an end portionof main body 152. In order to adjust the angular travel of rod 72,cylinder cap 100 is removed from body tube 70 and adjustment tool 150 isinserted into the body tube 70 so that dowel pins 158 engage bores 146of piston 76. By rotating piston 76 relative to rod 72 via theadjustment tool 150, the threaded engagement of the piston 76 to the rod72 causes piston 76 to adjust the distance between piston stop 82 andpiston 76. The distance between piston stop 82 and piston 76 determinesthe angular travel of rod 72 and delivery arm 74. Thus, the angularorientation of the delivery arm 74, in the fully extended position, canbe easily adjusted by simply removing cylinder cap 100 and adjusting thepiston 76 using adjustment tool 150.

In order to adjust the “throw” or distance of travel for the rod 72, thepiston stop 82 can be adjusted relative to rod 72. In other words, byadjusting the threaded engagement between piston stop 82 and rod 72, thedistance between piston stop 82 and cam follower 88 is adjusted. Thisdetermines the “throw” of rod 72 and delivery arm 74. Accordingly, inorder to utilize the rivet delivery device 60 of the present inventionwith different sized rivets having different length mandrels, the“throw” of the rivet delivery device can be easily adjusted by pullingthe cam sleeve 94 along with rod 72, delivery arm 74 and piston 76 outfrom body tube 70 so that the piston stop 82 can be rotatably adjustedrelative to the threaded portion 78 of rod 72. The “throw” of the rivetdelivery device 60 is adjusted when a changeover to a different sizedrivet is required. Adjustment of the angular movement of the rod 72 anddelivery arm 74 may be necessary if transfer bushing 114 of delivery arm74 is not properly aligned with the nose piece 124 of the installationtool 126 in the fully extended rivet delivery position. It isanticipated that the rivet delivery device could be modified so that the“throw” could be adjusted in the manner that the angular travel isadjusted and the angular travel could be adjusted in a similar mannerthat the “throw” is adjusted in the embodiment as discussed above.

With reference to FIGS. 17-24, the improved escapement mechanism 26 ofthe present invention will now be described. Escapement mechanism 26includes an escapement housing 170 which is mounted at a bottom portionof track 24. A rivet nesting block 28 is slidably received in theescapement housing 170 and includes a recessed portion 172 for receivingand supporting a rivet R. Nesting block 28 is connected to a drive rod174 which is connected to a piston (not shown) which is disposed in apneumatic cylinder 176. Drive rod 174 includes an end fitting 178 havinga head portion which is received in an elongated slot 180 disposed in aside of the nesting block 28. Slot 180 has a T-shaped cross section forreceiving the head portion of end fitting 178. Recessed rivet receivingslot 172 has a shoulder portion 182, as shown in FIG. 23 on which therivet flange rests, and a mandrel receiving slot portion 184 whichreceives a mandrel therein. The rivet receiving slot 172 and mandrelreceiving slot 184 are each provided with a beveled edge portion 172 a,184 a, respectively. The beveled edge portions 172 a, 184 a provide acamming surface to roll the second rivet in line out of the way and pushit back up the track 24 as the nesting block 28 moves to a deliveryposition, thus preventing a jam in the escapement mechanism 26. Thenesting block 28 is removable from the escapement housing 170 as shownin FIG. 19 simply by lifting upward on the nesting block 28 so that theend fitting 178 of drive rod 174 is slid free of slot 180. During achangeover, in order to utilize the escapement mechanism 26 of thepresent invention with different sized rivets, nesting blocks 28 havingdifferent sized rivet receiving slots 172 can be quickly and easilychanged and connected to the end fitting 178 of drive rod 174.

Nesting block 28 is secured within escapement housing 170 by placing atop plate 190 over escapement housing 170. Top plate 190 includes a pairof holes 192 which receive locating pins 194 which extend upward fromescapement housing 170. Locating pins 194 hold top plate 190 in place asa thumb screw assembly 196 secures the top plate 190 to the escapementhousing 170. Thumb screw assembly 196 includes a swing bolt 197pivotally mounted to the escapement housing 170 by a pivot pin 198.Swing bolt 197 is received within a slot 200 disposed in a side of thetop plate 190 and the thumb nut 202 is tightened downwardly onto the topsurface of top plate 190.

A clamp ring 204 is provided on the top plate 190 and surrounds anescapement guide tube 206. The rivet delivery tube 30 is attached to theescapement guide tube 206 and held in place with clamp ring 204. Asource of pressurized air in the form of pneumatic tube 208 is providedin the bottom of escapement housing 170 which forces a rivet R which isin the rivet receiving slot 172 through rivet delivery tube 30. Thenesting block 28 is movable from a first loading position, wherein arivet is received from track 24 and supported in the rivet receivingslot 172 of nesting block 28. Cylinder 176 is then pressurized viapneumatic tube 210 (see FIG. 3) to force the drive rod 174 to move thenesting block 28 to a second, rivet delivery position, wherein the rivetreceiving slot 172 communicates with the pneumatic tube 208 and theescapement guide tube 26 disposed on top plate 190 so that rivet R isdelivered through rivet delivery tube 30. Another source of pressurizedgas communicates with cylinder 176 via pneumatic tube 211 (see FIG. 3)for returning the drive rod 174 and nesting block 28 to the hose orloading position.

During a changeover to a different sized rivet, or during cleaning ormaintenance, the top plate 190 can be easily removed from escapementhousing 170 by loosening thumb nut 202 and pivoting the swing bolt 197away from the top plate 190 so the top plate 190 can be picked up off ofescapement housing 170. At this time, nesting block 28 can be removed bysimply lifting upward on the nesting block 28 to disengage the nestingblock 28 from the end fitting 178 of drive rod 174 as fitting 178 slidesout of slot 180. The rapid changeover, cleaning and maintenancecapabilities which are provided by the improved escapement mechanism 26enhances the efficiency of the riveting system of the present invention.

With reference to FIG. 3, the rivet setting tool 12 includes a pullinghead 43 which includes a hydraulic piston 43 a within a machinedaluminum housing 43 b. The piston is connected to jaw case 44 via acoupling so that during activation, i.e., hydraulic pressure supplied bya hydraulic hose 212 on the face of the hydraulic piston 43 a, the jaws44 ramp off a nose piece, and engage the rivet mandrel. Continued travelprovides enough force and stroke to effectively set the average rivet.The pulling head 43 employs air pressure via pneumatic tube 214 on theopposite side of the hydraulic piston 43 a to return the piston 43 a toits full forward position once hydraulic pressure is removed.

The hydraulic supply hose 212 is connected to the remote intensifier 40.As shown in FIG. 25, the remote intensifier 40 includes an intensifierchamber 220 which is provided with an intensifier chamber sleeve 222. Anair piston 224 is slidably received in the intensifier chamber 220 andis provided with a seal 226 which engages intensifier chamber sleeve222. A rod 228 is attached to air piston 224 and extends into a sealedcylindrical opening in a ram housing 230 which is filled with hydraulicoil 232. A seal 233 is provided between the rod 228 and the housing 230.A source of pressurized air in the form of pneumatic tube 234 isconnected to a valve 236 which is connected to a quick dump exhaustvalve 238 which communicates with a first end of intensifier chamber220. A second supply of pressurized air in the form of pneumatic tube240 is provided in communication with a second end 242 of intensifierchamber 220. A quick dump exhaust valve 244 is provided in communicationwith the second end 242 of intensifier chamber 220. The ram housing 230is connected to the hydraulic hose 212 by a plurality of fittings.

A high pressure hydraulic pressure switch 250 and a low pressurehydraulic pressure switch 252 are provided in communication with thehydraulic fluid passage 212. Air pressure applied to the air piston 224forces the rod 228 to displace a column of hydraulic oil 232 with asmaller cross-sectional area. The volume of air acting on the area ofthe piston forces the piston 224 and rod 228 upward. The differential inarea between the air piston 224 and the top of the rod 228 allows thegeneration of a high hydraulic pressure from a low air pressure.

As the air piston 224 moves upward, exhaust dump valve 244 opens to ventair building up on top of the piston 224. The high pressure column ofoil 232 flows through the hydraulic hose 212, and forces the hydraulicpiston 43 a of pulling head 43 back, thus setting the rivet.

Upon mandrel break, as detected by hydraulic switches 250 and 252 asdescribed herein, the controller 34 stops activating the valve 236, andstarts activating a remote valve (not shown) supplying a regulatedsupply of air through quick dump exhaust valve 244 and on top of airpiston 224. The combination of the air behind the piston 43 a of thepulling head 43 disposed within the rivet setting tool 12, and the airbubble on top of the air piston 224 quickly returns the pulling head 43and jaw case 44 to the retracted position. Return air on top of the airpiston 224 cannot build up in pressure since the top or second end 242of the chamber 220 is vented out around the intensifier chamber sleeve222 and out to atmosphere. The sleeve 222 is provided with a pluralityof recess portions 222 a at an upper edge thereof forming vent passages.The chamber 220 is provided with a plurality of vent holes 220 a in alower portion thereof. The differential in the air flow entering the topof the chamber 220, versus its ability to leak out past the sleeve 222is what assists the air piston 224 in returning. Without venting the airin the upper portion of intensifier chamber 220, it would be possible tosupply too much pressure to the top of the air piston 224 which coulddraw the rod 228 out too fast, and force the introduction of air intothe hydraulic passage past the seal 233. The venting of the top portion242 of the intensifier chamber 220 to atmosphere limits that possibilityby limiting pressure build up. Air supply to the top of the air piston224 is controlled by the riveting system controller 34 and shuts offafter approximately one second.

In order to achieve a rapid loading and setting cycle, the remoteintensifier design of the present invention provides a low pressurebubble of air on top of the intensifier piston 224 to assist the returnof the entire system, and cut the return speed of the pulling head 43 ofthe installation tool 126. By utilizing the intensifier 40 of thepresent invention, the return speed has been cut approximately in halfin comparison to simply utilizing air pressure on the back of the pistonof the pulling head 43 forcing the oil in front of the piston of thepulling head 43 back through the hose 212 and pressing air piston 224back to its beginning position.

The rivet setting and mandrel collecting sequence of events is describedwith reference to FIG. 3. When trigger 66 is depressed, the controller34 activates the remote intensifier 40 to supply hydraulic fluid to thepulling head 43 to drive the pulling head 43 back. At the time thetrigger 66 is depressed, the controller 34 starts a “rivet setting”window or time period. The jaw case 44 then engages the rivet mandreland starts the setting process. As hydraulic pressure builds, the highand low pressure switches 250, 252, respectively, witness the increasein pressure as setting occurs, and set a latch. When the high pressureswitch 250 drops low again, the controller deduces that the rivet hasbeen set.

FIG. 27 shows a typical rivet set signature wherein at time t₀activation of the trigger 66 begins a rivet setting sequence and a rivetsetting window is started. At time t₁, the mandrel is engaged by thejaws 44 and the hydraulic pressure begins to build low pressure. Lowpressure switch 252 senses the hydraulic pressure rising above the lowpressure limit P_(L) at time t₂ while the high pressure sensor 250senses the hydraulic pressure climbing above the high pressure limitP_(H) at time t₃. At time t₄, the mandrel breaks and the hydraulicpressure rapidly drops and at time t₅, the pressure drops below the highpressure limit P_(H) and is sensed by the high pressure switch 250 andthe controller 34 deduces that the rivet has set. At this time,activation pressure to the remote intensifier 40 stops and return air isstarted, causing the tools pulling head 43 to return concurrently. Thecontroller 34 starts a mandrel collection window to monitor thecollection of the mandrel M. The time interval can be set, for example,at twenty-fifty percent longer than the nominal time for the mandrel tobe fully released and collected (for example approximately three secondsfor a typical mandrel collection time of two seconds). The tool jaws 44open as the pulling head 43 returns and the mandrel M is released and avacuum pressure draws the mandrel past the mandrel sensor 50 and intothe collection bin 44. As the mandrel passes the mandrel sensor 50, themandrel collection window is reset. The rivet delivery device 60 loads anew rivet into the nose piece 124 of the tool as the tool returns fullforward. Since the high setting/loading speed makes it possible to haveas many as two mandrels in the collection path at once, two (orsometimes more) separate mandrel collection windows are required. Withtwo mandrel collection windows, the first mandrel collection windowbecomes available for a third rivet as soon as the first mandrel passesthe mandrel sensor 50. These two timers (or windows) are continuouslyreused again and again throughout the process. If a jam were to inhibitcollection of the mandrels, this would be witnessed by the mandrelcollection window timing out before the mandrel sensor 50 detects amandrel's passage. With two mandrel collection windows, there could beas many as two mandrels in the path, but no more since this faultinhibits all setting functions until cleared and reset.

The rivet setting tool 12 uses no sensor to determine if there is arivet loaded in the tool. The control system assumes the rivet deviceachieves loading on every attempt. It is during the setting process thatthis is proven true, or not, by monitoring the pressure switches 250,252. If the switches 250, 252 detect pressure within the rivetingsetting window, i.e., within an amount of time for the pulling head 43to travel almost fully back (for example 40 ms), it knows a rivet waspresent and proceeds as above. If there were no rivet in the nose piece124 when the trigger 66 is activated, the switches 250, 252 would see nobuild-up of pressure within the rivet setting window and would not starta mandrel collection window, but would rather initiate the rivetdelivery device 60 reloading sequence. As compared with prior automatedrivet setting systems which utilize a mandrel collection system, thecontrol sequence of the present invention improves the speed ofoperation of the rivet setting system. With previous systems, the rivetsetting tool was not allowed to reload until the previously spentmandrel is received past the mandrel sensor. However, with the presentinvention, it is possible to set a first rivet and to subsequently set asecond rivet prior to the mandrel reaching the mandrel sensor associatedwith the mandrel collection system. Thus, the operator does not have towait for the mandrel to be sensed before applying a second rivet.

Furthermore, with the control system of the present invention, once amandrel break is detected, the supply of hydraulic pressure to thepulling head can be halted so that the pulling head can be immediatelyreturned to its starting position, ready to begin another rivet settingsequence. Thus, the speed of operation of the rivet setting tool of thepresent invention is increased since the system does not have to waitany longer than necessary to reset itself after mandrel break isdetected.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

What is claimed is:
 1. A rivet setting tool, comprising: a pulling headincluding a hydraulic piston disposed within a housing; a jaw caseconnected to said hydraulic piston such that said jaw case is driven bysaid pulling head to engage a rivet mandrel, whereby continued travel ofsaid hydraulic piston supplies force to effectively set a rivet; aremote intensifier including an air piston disposed in a piston chamberand a hydraulic ram connected to said air piston and extending into aram housing which is connected to a hydraulic passage in communicationwith said pulling head, said air piston having a larger cross-sectionalarea than said hydraulic ram; a first supply of pressurized gascommunicating with a first end of said piston chamber; and a secondsupply of pressurized gas communicating with a second end of said pistonchamber and wherein said piston chamber includes a chamber sleeve andsaid second end of said piston chamber is vented around said chambersleeve to atmosphere.
 2. The riveting tool according to claim 1, whereinsaid chamber sleeve includes at least one recess portion at an upperedge thereof forming a vent passage for air in said second end of saidpiston chamber.
 3. The riveting tool according to claim 1, wherein saidfirst end of said piston chamber is provided with a quick dump exhaustvalve.
 4. The riveting tool according to claim 1, wherein said secondend of said piston chamber is provided with a quick dump exhaust valve.5. The riveting tool according to claim 1, wherein said first end ofsaid piston chamber is provided with a quick dump exhaust valve.
 6. Theriveting tool according to claim 1, wherein said second end of saidpiston chamber is provided with a quick dump exhaust valve.
 7. Theriveting tool according to claim 1, wherein said hydraulic ram includesa rod connected to said air piston.